1. Field of the Description
The present description relates, in general, to three dimensional (3D) projection technology including 3D glasses worn by viewers to perceive 3D imagery, and, more particularly, to 3D stereo display systems that are adapted for creating 3D effects or imagery without the need for 3D projectors and/or 3D content.
2. Relevant Background
Recently, there has been an increased interest in providing movies and other image-based content to viewers in 3D form, and there has been significant research in the past on technologies to produce 3D imagery. Most 3D technologies require the viewers to wear 3D glasses (or other headgear or other filters, which will be labeled “3D glasses” herein) such that left eye images are received by their left eye and right eye images are received by their right eyes, and the combination of these right and left eye images are perceived by the viewers as 3D images or imagery.
Polarization and wavelength multiplex visualization are the two main types of 3D technologies that are in widespread use in cinema applications and in other entertainment venues including amusement or theme parks (e.g., in 3D rides, 3D displays, and other park attractions). With polarization or linear polarized technology, the viewer wears low-cost eyeglasses that contain a pair of different polarizing filters. Each of the viewer's eyes sees a different image (right eye image and left eye image that are provided by cameras (actual or virtual) spaced apart the intraocular distance) because the filters pass only light having a particular polarization (i.e., matching the eyeglass filter) and block the light polarized differently (e.g., in the other polarization direction). Linear polarized technology is used to produce a 3D effect by projecting the same scene into both eyes but depicted from slightly different offsets to create the necessary parallax to provide a 3D image. Use of this technology has the advantage of low cost glasses but is inefficient with light causing loss of brightness and requires a silvered screen to main polarization.
Due to these and other disadvantages, there has been increased interest in the use of wavelength multiplex visualization (also known as interference filters or comb filters and generally labeled “WMV” or “WMV technology” herein). There are at least two main types of WMV technology used to provide 3D displays. In the first type of WMV technology-based 3D systems (e.g., Dolby 3D systems provided by Dolby Laboratories, Inc. or other WMV-based systems provided by other developers/distributors), a single projector is used that can project both left and right eye images using an alternate color wheel placed in the projector. The color wheel contains one more set of red, green, and blue filters in addition to the red, green, and blue filters found on a typical color wheel. The additional sets of three filters are able to produce the same color gamut as the original three filters but transmit light at different wavelengths. 3D glasses with complimentary dichroic filters in the lenses are worn by a viewer that filter out either one or the other set of the three light wavelengths. In this way one projector can display the left and right stereoscopic images simultaneously, e.g., by a stereoscopic projection process that is labeled wavelength multiplex visualization or WMV (or is categorized as one form of wavelength multiplex visualization that may also be considered a narrowband-based WMV or a WMV implementing one or more narrowband sources of illuminating light paired with 3D stereo glasses worn by a viewer to properly filter light from these sources).
This first type of WMV-based 3D system may be desirable because it does not require a silvered screen and can be both rear projected and front projected on most surfaces. Another advantage of this technology is that it can be viewed from multiple points of view clearly and effectively, and it provides relatively uniform brightness across the projected surface regardless of the viewer's point of view. These WMV-based 3D systems also can be used in both theater and other entertainment settings where the viewer may have to tilt and move their heads whereas this is not the case with polarization-based 3D display systems. Presently, the 3D glasses are relatively expensive with a common example being $15 USD in 2015 such that the glasses are not typically considered disposable.
A second type of WMV-based 3D system (e.g., a Christie 6P system available from Christie Digital Systems USA, Inc. or another designer/distributor of this second type of WMV) is built on a fiber-coupled, 6-primary projection system architecture rather than filtered or polarized broad-spectrum white light. In some systems using this second type of WMV, 6-Primary (“6P”) laser projectors employ two sets of red, green, and blue (RGB) laser lights, with one set being for the left eye and one, with slightly different wavelengths, for the right eye, which is why this second type of WMV-based 3D system is considered to employ or provide wavelength multiplex visualization. The viewer wears 3D glasses in these systems that filter out the different wavelengths and direct the light to the intended eye. This second type of WMV may be thought of as a laser projector-based WMV. There are a number of advantages associated with these systems including: effectiveness with light as almost 90 percent of the light from the projector makes it to the viewer's eye; does not require a silvered screen and can be both rear and front projected on nearly any surface; can be viewed from multiple points of view with no hot spot and has uniform brightness without regard to a viewer's point of view; can be used in applications where a viewer may tilt or move their head; and has a broad color gamut. As with the first type of WMV system, the stereo glasses for this second type of WMV system are expensive (e.g., $20 to $25 USD/pair), and the light module and other projection components are also relatively expensive.
An ongoing challenge for many applications is how to integrate 3D projection or display systems in larger facilities rather than in the more contained theater setting. For example, many amusement parks include 3D theaters with long queues and 3D ride systems that now utilize wavelength multiplex visualization (“WMV”) technology (such as Dolby 3D, Christie 6P, or the like) such that visitors (or “viewers”) are now wearing stereo glasses adapted for use with such technologies (such as Dolby or other stereo glasses) rather than polarized glasses. These projection systems work through the realization that all humans see all colors using only the three color sensors in the eye for red, green, and blue. All other colors are synthesized by humans from mixtures of these three fundamental colors. As discussed above, for example, the first type of WMV system functions by splitting the red, green, and blue images to be displayed/projected into two narrow wavelength bands (e.g., Red1, Green1, and Blue2 Blue1 or RGB1) and Red2, Green2, and Blue2 or RGB2). Then, for a left stereo image, the projector (or projectors if two are used) may project light with the wavelength bands for RGB1 and, for a right stereo image, the projector may project light with the wavelength bands for RGB2. The color separation is done with very narrowband color filters or lenses provided in the Dolby 3D and other stereo glasses (e.g., with three filters overlaid for each of the viewer's eyes) such that the lens over the left eye only passes the RGB1 light or images while the lens over the right eye only passes the RGB2 light or images.
Projectors for systems employing wavelength multiplex visualization are expensive such that their use is generally limited to large-scale theatrical experiences. However, in amusement park rides and some theater settings, the viewers may be offered and be wearing the 3D stereo glasses designed for these systems outside of the theater or projection space. For example, a 3D-based ride may include one or more theater-type portions where a WMV projector(s) (e.g., a Dolby 3D projector, Christie 6P projector(s), or the like) is used to project 3D images viewable by the ride participants. However, the ride participants will be wearing the 3D stereo glasses in other portions of the ride, which may be 50 to 90 percent of the length of the ride, where there is no 3D imagery being projected. One solution would be to provide the 3D projectors along the entire length of the ride, but this solution is typically discarded as being prohibitively expensive.
Hence, there remains a need for display systems and methods for providing 3D imagery to viewers such as in locations or spaces outside of a conventional 3D theater setting (e.g., in the queue to or from the theater) and outside of portions of a ride configured for 3D projection.